This invention relates to a unique position for an oil supply cross-hole in the orbiting scroll of a scroll compressor.
Scroll compressors are becoming widely utilized in refrigerant applications. In a scroll compressor first and second scroll members each have a base and a generally spiral wrap extending from a base. The wraps interfit to define compression chambers. One of the scroll members is caused to orbit relative to the other, and as the scroll member orbits the compression chambers decrease in volume to compress an entrapped refrigerant.
One challenge with scroll compressors involves holding the two scroll members together as the refrigerant begins to be compressed. The opposed wraps must contact the base of the opposed scroll member to define the compression chambers. However, the entrapped refrigerant creates a separating force tending to bias the two scroll members away from each other. Thus, it is typical in scroll compressors to tap a portion of the refrigerant to a back pressure chamber. The back pressure chambers are typically defined by seals within a crankcase which supports the orbiting scroll. Further, outwardly of the seals an Oldham coupling constrains the orbiting scroll to orbiting movement, even though it receives a rotary input from a rotary motor.
One challenge in the prior art is supplying adequate lubricant to the interface between the orbiting scroll and the crankcase to provide sufficient lubrication to both the coupling and the seals.
The crankcase is secured to the non-orbiting scroll through a plurality of structures called crankcase towers. In the prior art, a cross-hole extends through the base of the orbiting scroll to supply lubricant to the outer periphery of the orbiting scroll at a circumferential location generally aligned with one of the crankcase coupling.
In the prior art, the cross-hole was formed at a location slightly upstream of the suction inlet into the scroll compressor. With such a location, there is the potential of lubricant being entrained into the refrigerant being compressed. This is undesirable.
In the disclosed embodiment of this invention, a cross-hole extends from the inner periphery of the bore of the orbiting scroll radially outwardly to the outer peripheral surface of the orbiting scroll to supply lubricant against a crankcase tower. Preferably this cross-hole is circumferentially downstream from the beginning of the orbiting scroll wrap, and less than 180xc2x0 downstream from the beginning of the orbiting scroll wrap. More preferably, the cross-hole is between 30xc2x0 and 90xc2x0 downstream of the beginning of the scroll wrap. In an illustrated embodiment the cross-hole is a few degrees above 80 downstream of the beginning of the scroll wrap.
In this location, the cross-hole is directed at a crankcase tower, which is desirable for providing adequate lubrication. Further, the position is far enough downstream that lubricant will not likely be drawn into the compression chambers in any undue quantities.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.